Because AA is usually only 1px thick, you can usually reuse other colours for it; it's perfectly fine if the hues are off, as long as the values are what you need, because at 1px thickness, the hue generally doesn't read anyway. Adding new colours just for AA is often unnecessary :D If you reduce this to the 32 colours you used on the character, the AA is still quite effective. If you add in a few more colours in addition to the 32 (e.g. to get to 40 or 48 total), it's barely distinguishable from your 94-colour version unless you're looking for the differences.
In addition, people are pretty bad at distinguishing colours that are very light or very dark, so you don't need to have such small steps for AAing between the white and yellow, and if you were to replace the black outline with the dark purple you used on the eyes, I doubt anyone would notice.
Cute pixels!